gh-96: Pointer args preserve aliasing.

Author: python-processing-unit

src/interpreter.c

@@ -1250,6 +1250,7 @@ Value eval_expr(Interpreter* interp, Expr* expr, Env* env) {
                 Value arg_val = value_null();
                 int arg_from_pos = -1;
                 int arg_from_kw = -1;
+                Expr* source_node = NULL;
 
                 bool provided = false;
                 // positional provided?
@@ -1312,6 +1313,12 @@ Value eval_expr(Interpreter* interp, Expr* expr, Env* env) {
                     }
                 }
 
+                if (arg_from_pos >= 0) {
+                    source_node = expr->as.call.args.items[arg_from_pos];
+                } else if (arg_from_kw >= 0) {
+                    source_node = expr->as.call.kw_args.items[arg_from_kw];
+                }
+
                 if (!provided) {
                     char buf[128];
                     snprintf(buf, sizeof(buf), "Missing argument for parameter '%s'", param->name);
@@ -1326,6 +1333,65 @@ Value eval_expr(Interpreter* interp, Expr* expr, Env* env) {
                     return value_null();
                 }
 
+                if (source_node && source_node->type == EXPR_PTR) {
+                    const char* target_name = source_node->as.ptr_name;
+                    if (!target_name) {
+                        interp->error = strdup("Invalid pointer target");
+                        interp->error_line = expr->line;
+                        interp->error_col = expr->column;
+                        if (arg_from_pos >= 0) {
+                            value_free(pos_vals[arg_from_pos]);
+                            pos_vals[arg_from_pos] = value_null();
+                        }
+                        if (arg_from_kw >= 0) {
+                            value_free(kw_vals[arg_from_kw]);
+                            kw_vals[arg_from_kw] = value_null();
+                        }
+                        for (int t = 0; t < pos_argc; t++) value_free(pos_vals[t]);
+                        free(pos_vals);
+                        for (int t = 0; t < kwc; t++) value_free(kw_vals[t]);
+                        free(kw_vals);
+                        env_free(call_env);
+                        return value_null();
+                    }
+
+                    if (env_set_alias(call_env, param->name, target_name, param->type, true)) {
+                        if (arg_from_pos >= 0) {
+                            value_free(pos_vals[arg_from_pos]);
+                            pos_vals[arg_from_pos] = value_null();
+                        }
+                        if (arg_from_kw >= 0) {
+                            value_free(kw_vals[arg_from_kw]);
+                            kw_vals[arg_from_kw] = value_null();
+                        }
+                        continue;
+                    }
+
+                    if (interp->error) {
+                        free(interp->error);
+                        interp->error = NULL;
+                    }
+                    char buf[256];
+                    snprintf(buf, sizeof(buf), "Cannot bind pointer argument to parameter '%s'", param->name);
+                    interp->error = strdup(buf);
+                    interp->error_line = expr->line;
+                    interp->error_col = expr->column;
+                    if (arg_from_pos >= 0) {
+                        value_free(pos_vals[arg_from_pos]);
+                        pos_vals[arg_from_pos] = value_null();
+                    }
+                    if (arg_from_kw >= 0) {
+                        value_free(kw_vals[arg_from_kw]);
+                        kw_vals[arg_from_kw] = value_null();
+                    }
+                    for (int t = 0; t < pos_argc; t++) value_free(pos_vals[t]);
+                    free(pos_vals);
+                    for (int t = 0; t < kwc; t++) value_free(kw_vals[t]);
+                    free(kw_vals);
+                    env_free(call_env);
+                    return value_null();
+                }
+
                 Value bind_val = arg_val;
                 bool used_coercion = false;
                 if (value_type_to_decl(bind_val.type) != param->type && param->coerced) {

tests/test2.pre

@@ -258,6 +258,16 @@ DEL(x)
 DEL(y)
 PRINT("Pointers: PASS\n")
 
+PRINT("Testing pointer arguments...")
+INT: ptr_arg = 0d5
+FUNC INT: SET_ZERO(INT: target){
+    target = 0d0
+}
+SET_ZERO(@ptr_arg)
+ASSERT(EQ(ptr_arg, 0d0))
+DEL(ptr_arg)
+PRINT("Pointer arguments: PASS\n")
+
 PRINT("Testing ASSIGN inline operator...")
 ! typed first assignment should declare, assign, and return the value
 ASSERT(EQ(ASSIGN(STR: as_s, "foo"), "foo"))